JP2010072643A - Toner having fluorescence agent and toner set including the toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner set comprised of a plurality of toners including a number of toners. <P>SOLUTION: At least one toner but less than all toners of the toner set includes binder, colorant and fluorescence agent and remaining additional toners are includes binder and colorant and free of fluorescence agent, wherein at least a first toner grouping and a second toner grouping of the toner set form a combination, the first and second toner groupings of the combination exhibiting a substantially same color under ambient light conditions upon image formation, the first toner grouping and the second toner grouping of the combination contain a different amount of the fluorescence agent, wherein upon exposure to activating energy, the fluorescence agent fluoresces to cause a visible change in the color of a pattern formed in an image by the first toner grouping as compared to the second toner grouping. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  Described herein is a set of toners, the set comprising at least two different groups of toners that form a combination that can exhibit substantially the same color under ambient light conditions, the toner of the toner set At least one toner, less than all of the toners, includes an amount of a fluorescent agent that fluoresces when exposed to activation energy and contains at least one fluorescent agent. A visible change is caused in the color of the toner group having toner.

  The fluorescent mark as described in Patent Document 1 is an excellent security feature. Since four colors of cyan, yellow, magenta, and black are usually used to determine the color space, there are many color combinations that exhibit exactly the same color in the color space. Fluorescent marks can take advantage of this by using two different color combinations that exhibit the exact same color but have completely different UV behavior. This can be done by controlling the paper coverage and creating a sophisticated fluorescent signal for the combination exposing the maximum amount of paper. This combination presents a uniform color to the viewer under visible light, but under black light, the fluorescence from the paper gives a visible graphic or text image. A security image can contain variable data through the use of a “pattern ink” construct in a standard page description language.

  However, the effect of the fluorescent mark depends on the presence of a fluorescent agent such as a fluorescent whitening agent in the substrate, and as a result, the use of the fluorescent mark may be limited. For example, fluorescent marks may be limited by the spectral characteristics inherent in the pigment and are typically used only in light colors. Toners that can utilize fluorescence in a manner that does not depend on the recording medium material are desired.

US Patent Application Publication No. 2007/0262579 US Pat. No. 3,590,000 US Pat. No. 3,800,588 US Pat. No. 6,214,507

  An enhanced security toner package is desired that includes toner that can function as a standard toner but includes enhanced fluorescence attributes and can be used in almost any color, including dark colors such as black. The

  This specification describes a toner, particularly an emulsion aggregation toner, which contains a fluorescent agent that is formed with the toner when the fluorescent agent is exposed to sensitive activation energy. The resulting image provides a sharp luminescent image of a color different from that shown under ambient light conditions. An image formed from this toner and under ambient light conditions can exhibit substantially the same color and gloss response as an image formed from a similar toner but without a fluorescent agent. Thus, a toner set can be formed using toner containing a fluorescent agent, allowing security features to be formed in images obtained from this toner set.

  Desirably, the toner set comprises a number of toners, such as at least two toners, for example 2 to 10 toners, 2 to 5 toners or 2 to 4 toners, Substantially the same color can be achieved with at least two different toner groups in the set. A combination refers to, for example, separate toner groups, each group containing one or more toners from a toner set. In full color systems, typically at least four different color toners are used in the toner set, respectively cyan (C), yellow (Y), magenta (M) and black (K). The same color can be achieved using a number of different toner combinations in the toner set. In color printing, this is often referred to as conditional color (metamerism), and color images are printed using different cyan, magenta, yellow and black toners, and various different CMYK combinations are typically used by human observers. Bring the same color. For example, a first toner group of cyan, yellow, and magenta toner, each with an exact ratio, eg, 33.33%, forms the same black color as black toner (which constitutes the second toner group). be able to. Thus, in this example, a toner combination that achieves the same color would include a first toner group of cyan, yellow, and magenta toners and a second toner group of black toner. Of course, if the toner set contains two toners of the same color, for example if one black toner contains a fluorescent agent and the other black toner does not contain a fluorescent agent, then these two toners are used respectively. The same color can be achieved. Thus, for a non-full color system, typically two toners, each having the same color, are included, and the toner combination consists of a first group of first black toner and a second black toner. A second group of toner is included.

  In the toner set herein, at least one but not all of the toner set includes a binder, a colorant, and a fluorescent agent, and optionally more than one toner in the toner set is also a binder, a colorant. The remaining toner in the toner set includes a binder and a colorant but no fluorescent agent. At least the first toner group and the second toner group of this toner set form a combination that exhibits substantially the same color under ambient light conditions when an image is formed. Since the amount of the first toner is different from that of the second toner group, the amount of the fluorescent agent is different. A combination to achieve a given or predetermined substantially the same color must contain different amounts of fluorescent agent so that it is measurable or detectable when exposed to activation energy. Don't be. This achieves some formulations as described herein, for example (1) achieves substantially the same color, the first group contains a fluorescent agent and the second group does not contain a fluorescent agent Toner combination, or (2) achieving substantially the same color and both groups contain a fluorescent agent, but the first group contains a different amount of fluorescent agent than the amount of fluorescent agent in the second group This can be achieved by including a toner combination.

  In the first embodiment, the toner combination that achieves substantially the same color is a combination in which the first group includes a fluorescent agent and the second group does not include a fluorescent agent.

  One example of this embodiment includes a full color toner set of CMYK, where black toner is the only toner containing a fluorescent agent. The first group will contain black toner. The second group will contain a combination of C, M and Y toners that achieve substantially the same black color. The second group does not contain a fluorescent agent.

  The toner set can thus contain toner in which one of the colors contains a fluorescent material, but no one of the same color and no fluorescent material is present. This is advantageous because it reduces the number of toners. For example, it is possible to have a set in which a fourth toner of black containing a fluorescent material is added to normal toners of cyan, magenta and yellow. A hidden message or code as security information can be created in black in this particular example by forming an image with a mixture of cyan, magenta and yellow to provide a first black area. The hidden message can be printed with black, the fourth toner containing fluorescent material. Under normal viewing conditions, the print appears entirely black. Under UV light, hidden messages become visible because they fluoresce when exposed to activating light. Alternatively, the background can be printed with fluorescent black toner, and the message can be printed with a combination of cyan, magenta, and yellow that is indistinguishable black.

  Another example of this first embodiment includes more than one toner of the same color, one of the same color toners contains a fluorescent agent, and the other toners of the same color do not contain a fluorescent agent , Including toner set. For example, if the toner set includes two black toners, one containing a fluorescent agent and the other not containing a fluorescent agent, the first group includes a black toner containing a fluorescent agent, The group includes black toners that do not contain a fluorescent agent.

  In a second embodiment, a toner combination that achieves substantially the same color is one group containing a different amount of fluorescent agent than the amount of fluorescent agent in the other group. This difference should be detectable to the extent that it can be measured during fluorescence, so that this difference can be used to form security features in the image. Detectable to the extent that it is measurable means that the difference in fluorescence is detected by any suitable mechanical reader or detector, such as a device known in the art, or human.

  In an embodiment, the toner set is an emulsion aggregation toner set composed of a plurality of emulsion aggregation toners, which exhibit substantially the same color in images viewed under ambient light conditions 2. Including at least two different toner groups.

Different color toners show different colors, that is, absorption characteristics in the formed image. For example, if the first toner represents yellow, the second different color toner may be different, yellow (different to human observers), or a completely different color, such as cyan or magenta. Shows a color like this. In this specification, substantially the same color means that, for example, two toner groups each form an image having an overall absorption characteristic in the visible wavelength region of the electromagnetic spectrum under normal ambient light conditions. This difference means that the human naked eye is virtually indistinguishable. Substantially the same color shall be two points on the color space where the values of L ^* , a ^* , and b ^* for each point are close enough, for example less than a predetermined ΔE number In an ideal situation, a value less than 1ΔE is considered the same for humans. However, in real-world applications, this idealized value is not usually achieved and a difference of 5ΔE is often sufficient, and in some cases even higher ΔE if the observer is subject to sufficient visual disturbance. acceptable. In this specification, a reference to a toner that exhibits substantially the same color refers to the color that the toner exhibits in an image formed using that toner.

  Thus, at least one color of the toner set can be achieved by two different groups of toner that exhibit substantially the same color of the set. Substantially the same color can be predetermined.

  Each of the toners in a toner set that includes two toners that exhibit substantially the same color can also be made to exhibit substantially the same gloss in an image formed from that toner. By doing so, it is possible to avoid the difference in gloss that occurs, for example, when the formed image is overcoated with a conventional transparent overcoat or toner. Gloss can be measured using a Gardiner gloss measurement device. In the embodiments herein, each of the toners used in the toner set comprising the two toners is made to have a substantially matched gloss. In this regard, each of the toners has an image having a gloss within the range of about 5 Gardiner gloss units (ggu) of each other, for example, from 0 to about 5 ggu, or from about 0.5 to about 3 ggu, or about 0 Images with gloss values in the range of .5 to about 2 ggu should be achieved. By doing so, the formed image with fluorescence ability does not show a substantial difference in gloss, so that the appearance of the image becomes uniform. The gloss exhibited by the toners herein can be stable over the fusing temperature range, from about 5 to about 75 gardiners when measured at 75 ° over a fusing temperature range of about 90 ° C. to about 120 ° C. Gloss units (ggu) can be, for example, from about 25 ggu to about 50 ggu.

  In an embodiment, the binder of the first toner containing the fluorescent agent is the same as the binder of the other toners that do not contain the fluorescent agent of the toner set. If the toner set has two toners of the same color, the colorants, eg pigments, of these two toners can be the same.

  The first toner group of the two toner groups may contain a fluorescent agent, and the second toner group may be substantially free of the fluorescent agent. In this case, the color of the first toner group is activated. The first toner group may include a fluorescent agent that is different in amount or type from the fluorescent agent of the second toner group, resulting in an activation energy for the fluorescent agent that changes upon exposure to energy. When exposed, the first toner group and the second toner group show different colors or light emission visually.

  For all of the toners in the toner set, the toner examples herein include toners that exhibit specific performance with respect to storage stability and particle size integrity, ie, until fused onto paper. It is desirable to have particles that remain intact and do not agglomerate. As ambient conditions change, the toner should also not substantially agglomerate until a temperature of about 50 ° C. to about 55 ° C. is reached. Resin and colorant toner composites should also exhibit acceptable tribocharging properties that vary depending on the type of carrier or developer composition.

The toner desirably exhibits a fixing temperature on the paper of, for example, from about 90 ° C. to about 210 ° C., such as from about 90 ° C. to about 150 ° C.
Toner fusing performance can be characterized as a function of temperature. The maximum temperature at which toner does not adhere to the fuser roll is called the hot offset temperature (HOT). When the fuser temperature exceeds HOT, some of the melted toner will adhere to the fuser roll during fusing and transfer to the substrate containing the subsequently developed image, for example, blur Resulting in an image. This undesirable phenomenon is called off-setting. Below the toner HOT is the minimum fixing temperature (MFT) of the toner, which is the lowest temperature at which acceptable adhesion of the toner to the support medium occurs, and can be determined by a crease test. The difference between MFT and HOT is called toner fusing latitude, ie, the temperature difference between the fusing temperature and the temperature at which the toner is offset onto the fuser. The allowable range of fusion should be as large as possible.
The toner herein can exhibit a minimum fixing temperature from about 90 ° C. to about 150 ° C. The toner can exhibit a glass transition temperature from about 45 ° C. to about 75 ° C. The toner exhibits satisfactory properties when used in a xerographic or electrophotographic process. Such properties can include the gloss described above, good C and A region charging, a fusing tolerance of about 15 ° C. to about 100 ° C., and substantially no vinyl offset. .

  Each toner is composed of small sized toner particles, for example having an average particle size from about 3 microns to about 12 microns, for example an average particle size from about 5 microns to about 9 microns. Small size toners such as those described above can be economically prepared by chemical processes involving the direct conversion of emulsion size particles into toner composites by aggregation and coalescence. When agglomerated and coalesced, the toner particles can have a geometric diameter distribution (GSD) of from about 1.05 to about 1.35, such as from about 1.10 to about 1.25. Is defined as the square root of D84 divided by D16. The particles have a relatively smooth particle morphology.

In the embodiment, the toner including a toner containing a fluorescent agent and a toner containing no fluorescent agent are each a linear amorphous resin, a branched amorphous resin, or a linear and branched amorphous resin as a binder. Both quality resins can be included, optionally with crystalline resins. In one embodiment, the binder can be composed of amorphous polyester, optionally mixed with crystalline polyester. The linear and / or branched amorphous resin and crystalline resin can each be an alkali sulfonated polyester resin. The alkali metal in each sulfonated polyester resin can be independently lithium, sodium, or potassium.
In embodiments, the binder comprises from about 10% to about 60% by weight of the binder weight, such as from about 10% to about 40% crystalline polyester, and from about 40% to about 90% by weight of the binder. Up to, for example, from about 60% to about 90% by weight of a linear amorphous polyester. All or part of the linear amorphous polyester in the binder can be replaced with a branched amorphous polyester. Branched here refers to a polymer having chains that are linked to form a crosslinked network. For example, if desired, 10% to 100%, such as 20% to 80% by weight of the linear amorphous polyester can be replaced with a branched amorphous polyester. The introduction of a branched polyester portion can be used to impart elasticity to the binder, which improves the offset characteristics of the toner while not substantially affecting the minimum fixing temperature (MFT).
In certain toners, the crystalline, linear amorphous and branched amorphous polyester materials of the binder can each be the same or different.

The crystalline resin can have various melting points, for example, from about 30 ° C. to about 120 ° C., such as from about 50 ° C. to about 90 ° C. The crystalline resin may be, for example, a number average molecular weight (Mn) of, for example, from about 1,000 to about 50,000, such as from about 2,000 to about 25,000, as measured by gel permeation chromatography (GPC). Can have. When determined by GPC using polystyrene standards, the weight average molecular weight (Mw) of the resin can be, for example, from about 2,000 to about 100,000, such as from about 3,000 to about 80,000. The molecular weight distribution (Mw / Mn) of the crystalline resin is, for example, from about 2 to about 6, more specifically from about 2 to about 4.
Crystalline resins can be prepared by a polycondensation process in which a suitable organic diol and a suitable organic diacid or diester are reacted in the presence of a polycondensation catalyst. In general, stoichiometric equimolar ratios of organic diol and organic diacid are used, however, in some cases, when the boiling point of the organic diol is from about 180 ° C. to about 230 ° C., an excess amount of diol is removed. Can be used and removed during the polycondensation process. The amount of catalyst used varies and can be selected, for example, from about 0.01 mole percent to about 1 mole percent of the resin. If organic diesters are used instead of organic diacids, alcohol by-products should be generated.

Linear and branched amorphous polyester resins may have a number average molecular weight in embodiments, for example, from about 10,000 to about 500,000, for example from about 5,000 to about 250,000, as measured by GPC. (Mn), for example, a weight average molecular weight (Mw) from about 20,000 to about 600,000, such as from about 7,000 to about 300,000, as determined by GPC using polystyrene standards, and For example, having a molecular weight distribution (Mw / Mn) from about 1.5 to about 6, more specifically from about 2 to about 4.
The linear amorphous polyester resin is generally prepared by polycondensation using an organic diol and a diacid or diester and a polycondensation catalyst. In the case of a branched amorphous polyester resin, the same material can be used and further includes a branching agent such as a polyvalent polyacid or polyol.

  Examples of the branching agent for use in forming the branched amorphous polyester include 1,2,4-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, and 2,5,7-naphthalenetricarboxylic acid. 1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylene-carboxylpropane, tetra (methylene-carboxyl) methane, and 1, Polyvalent polyacids such as 2,7,8-octanetetracarboxylic acid, their anhydrides, and their lower alkyl esters of 1 to 6 carbon atoms; sorbitol, 1,2,3,6 -Hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, , 2,4-butanetriol, 1,2,5-pentatriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3, Examples thereof include polyvalent polyols such as 5-trihydroxymethylbenzene, mixtures thereof, and the like.

  Examples of polycondensation catalysts for either crystalline or amorphous polyesters include tetraalkyl titanates, dialkyltin oxides such as dibutyltin oxide, tetraalkyltins such as dibutyltin dilaurate, butyltin oxide hydroxide Dialkyl tin oxide hydroxides, aluminum alkoxides, alkyl zinc, dialkyl zinc, zinc oxide, tin oxide, or mixtures thereof, such as those starting catalysts used to produce polyester resins. It is selected in an amount of about 0.01 mole percent to about 5 mole percent based on the acid or diester.

  In addition to the toner binder described above, the toners can each include at least one colorant. Various known suitable colorants, such as dyes, pigments, and mixtures thereof, in effective amounts, such as from about 1 percent to about 25 percent by weight of the toner, such as from about 1 percent to about 15 percent by weight of the toner, for example. Can be included in the toner.

The at least one colorant is desirably a non-fluorescent colorant. The toner colorant of the toner set containing the fluorescent agent must be a pigment. This is because when pigments are used to exhibit color and the fluorescent agent is dispersed in the toner binder, there is always sufficient space between the pigment particles to allow light to reach the fluorescent agent. It is. This is not necessarily the case when dyes are used as colorants, since the dyes are dispersed in the toner binder in the same way as fluorescent agents, especially in the case of dark colored toners such as black toners. Sufficient light may not reach the fluorescent agent. Therefore, fluorescence may not be realized properly.
A non-pigment colorant can be used as a colorant for a toner that does not contain a fluorescent agent in the toner set, but light is emitted so that desired fluorescence can be realized regardless of the order in which the toner is printed on the recording medium. It is desirable that all toners in the toner set contain a pigment-based colorant so that the fluorescent agent can be reached.

In toners that contain a fluorescent agent in the toner set, the fluorescent agent is a substance that emits or fluoresces in a color different from the color exhibited by ambient light in response to activation energy such as ultraviolet light or black light. is there. The activation energy or radiation can be, for example, a radiation source having a wavelength from about 100 nm to about 1100 nm, such as from about 150 nm to about 900 nm, or from about 200 nm to about 600 nm. Thus, the activation energy can be in the ultraviolet (UV), visible or infrared region, but the use of activating radiation in the UV region (about 100 nm to about 400 nm) is most common. Fluorescence may occur immediately upon exposure to activation energy, or may occur after overcoming some active phase. The appearing fluorescence may be reversible, but a period during which a color change or an appearance change of the image can be detected, such as from about 0.5 seconds to about 1 hour, such as from about 1 second to about 45 minutes, or about 5 seconds. Should last for about 30 minutes.
The total amount of fluorescent agent in the toner group can comprise from about 0.1% to about 75% of the total weight of the group. If both groups contain a certain amount of fluorescent agent, the amount of the two groups of fluorescent agents is at least about 3 percentage units, such as at least about 5 or 10 percentage units, so as to be detectable differently. Can be different. Thus, if the first group contains 50% fluorescent agent, the second group can contain 47% or less fluorescent agent, or 53% or more fluorescent agent.

  Suitable fluorescent agents include, for example, fluorescent dyes, fluorescent pigments, and inorganic surface functionalized quantum dot materials. Examples of fluorescent dyes suitable for use herein include rhodamine, fluorescein, coumarin, naphthalimide, benzoxanthene, acridine, those belonging to the dye system known as azo, and mixtures thereof.

The quantum dot material is a fluorescent inorganic semiconductor nanoparticle material. The light emission of the quantum dots is due to quantum confinement of electrons and holes. The advantage of quantum dots is that only one material can be used and can be tuned to emit any desired wavelength (color) depending on its size using the same synthesis process. Quantum dots are available from various companies, for example from Evident Technologies (Troy, NY).
In an embodiment, the quantum dot material used herein is a functionalized quantum dot. Surface functionalized quantum dots can have better compatibility with toner materials. Suitable functional groups present on the surface of the nanoparticle quantum dots for compatibility with the toner include, for example, from about 1 carbon atom to about 150 carbon atoms in length, such as from about 2 carbon atoms to about 125 carbons. Long chain linear or branched alkyl groups up to atoms, or from about 3 carbon atoms to about 100 carbon atoms can be mentioned. Other suitable compatibilizing groups include polyesters, polyethers, polyamides, polycarbonates and the like.

  In embodiments, the fluorescent agent is a lanthanide material or complex, such as a lanthanide chelate. Examples of lanthanide chelates are formed by chelation of organic ligands such as acetylacetone, benzoylacetone, dibenzoylmethane, and salicylic acid with lanthanide ions such as neodymium, europium, samarium, dysprosium, terbium ions, etc. What is done. Examples of such complexes include europium acetylacetonate, samarium acetylacetonate, neodymium benzoylacetonate, terbium salicylate, and dysprosium benzoylacetonate. The above chelate absorbs ultraviolet radiation and emits fluorescence in the visible region. For dark colored toners, the preferred fluorescent agent is DFKY-C7, a red emitting fluorescent dye from Risk Reactor.

  The fluorescent agent is in any suitable amount, for example from about 0.1% to about 50% of the toner weight, for example from about 0.5% to about 25%, or from about 0.5% to about 10%. Can be present in the toner.

  In an embodiment, the emulsion aggregation toner containing a fluorescent agent is a toner containing a polyester-based toner binder, a black pigment, and a lanthanide fluorescent agent as described above. The black pigment can be carbon black. Such a toner can be used in combination with a normal standard black toner or process black toner of substantially the same color.

  The toner can include additional optional ingredients including, for example, wax. When included, the wax can be present in an amount from about 1 to about 25 percent by weight of the toner, such as from about 5 to about 20 percent by weight. Examples of suitable waxes include polypropylene and polyethylene commercially available from Allied Chemical and Petrolite Corporation (eg, POLYWAX polyethylene wax from Baker Petrolite), Michaelman, Inc. And Eastman Chemical Products, Inc., a wax emulsion available from Daniels Products Company. EPOLENE N-15, Sanyo Kasei K. K. VISCOL 550-P, CARNABUBA wax, which is a low weight average molecular weight polypropylene available from Examples of functionalized waxes include, for example, amines, amides such as Micro Powder Inc. AQUA SUPERSLIP6550, SUPERSLIP6530, fluorinated waxes available from, for example, Micro Powder Inc. POLYFLUO190, POLYFLUO200, POLYSILK19, POLYSILK14, mixed fluorinated amide waxes, such as also available from Micro Powder Inc. MICROSPERSION 19, imides, esters, quaternary amines, carboxylic acids or acrylic polymer emulsions available from, for example, JONCRYL 74, 89, 130, 537, and 538, all available from SC Johnson Wax, and Allied Chemical and Petrolite Corporation and Mention may be made of chlorinated polypropylene and polyethylene available from SC Johnson Wax.

  The toner may also optionally include a positive or negative charge enhancing additive, for example, in an amount from about 0.1 weight percent to about 10 weight percent, or from about 1 weight percent to about 3 weight percent of the toner. it can. Examples of these additives include quaternary ammonium compounds including alkylpyridinium halides; alkylpyridinium compounds, organic sulfate and sulfonate compounds, cetylpyridinium tetrafluoroborate; distearyldimethylammonium methylsulfate; BONTRON E84 or E88 ( Ammonium salts such as Hodoya Chemical; mixtures thereof, and the like.

  The toner composition can also be blended with external additive particles including flow aid additives, and these additives can be present on the surface of the toner particles. Examples of these additives include metal oxides such as titanium oxide, tin oxide, mixtures thereof, colloidal silica such as AEROSIL, metal salts and fatty acid metal salts including zinc stearate, aluminum oxide, oxidation Cerium, as well as mixtures thereof. Each of the external additives can be present in an amount from about 0.1 weight percent to about 5 weight percent of the toner, more specifically from about 0.1 weight percent to about 1 weight percent. Some of the above additives are exemplified in Patent Document 2, Patent Document 3 and Patent Document 4.

The toner can be made by a variety of known methods, but the small size particles in the emulsion containing the other components of the toner aggregate to the proper toner particle size and then coalesce to the final It is desirable to be made by a known emulsion aggregation process that achieves toner particle shape and morphology.
In embodiments, the toner particles can have a core-shell structure, where the core is comprised of a binder, a colorant and a fluorescent agent, and the shell is comprised of an additional binder and no additional colorant. If desired, additional fluorescent agents can be included in the shell.

  The toner particles of all embodiments can be incorporated into the developer composition, for example, by mixing the toner particles with carrier particles to complete a two-component developer composition. The toner concentration in each developer ranges, for example, from about 1% to about 25% by weight of the total developer weight, such as from about 2% to about 15% by weight. Illustrative examples of carrier particles that can be selected for mixing with the toner include particles that can triboelectrically obtain a charge of the opposite polarity to that of the toner particles. Illustrative examples of suitable carrier particles include granular zircon, granular silicon, glass, steel, nickel, ferrite, iron ferrite, silicon dioxide and the like.

The toner in the toner set can be applied to a recording medium such as paper, plastic, cardboard, metal, etc. using any suitable xerographic or electrophotographic printing technique.
In embodiments, including, for example, magnetic brush development, one-component jumping development, hybrid scavengeless development (HSD), etc. to form an image with the toner set described herein, Any known type of image development system can be used in the image development apparatus. These development systems are known in the art and therefore further description of the operation of these devices to form an image is unnecessary here. A portion of the image as a whole first forms a latent image pattern for a given toner color on the photoreceptor surface, develops the latent image, and then forms an image portion of that color. It is sufficient to mention that the developed pattern can be formed by transferring it to a recording medium. After transfer to the recording medium, a fuser roll member can be used to assist in fixing the image to the recording medium. The fuser roll member is a contact fusing device known in the art, and heat and pressure from a roll are used to fuse toner to a recording medium such as paper. Typically, the fuser member can be heated to a temperature just above the toner fusing temperature, such as a temperature of about 80 ° C. to about 150 ° C. or higher.

  The first toner group of the combination can be transferred to the recording medium substrate before, during, or after the second group of patterns or images are transferred to the substrate. In embodiments where the combination includes two toners of the same color, the toner having a fluorescent agent can be transferred after transfer of the toner having substantially the same color but no fluorescent agent. In this way, when the toner containing the fluorescent agent has a pattern so as to cover at least some portion of the pattern formed by the toner not containing the fluorescent agent, it does not contain the fluorescent agent. A complete desired fluorescence effect can be achieved when exposed to activating radiation without concern for toner masking.

The fluorescent properties of fluorescent agents can be particularly useful in security applications. In embodiments, the presence of a fluorescent agent is not noticed by an observer when viewed with ambient light, but becomes noticeable when the fluorescent agent is exposed to fluorescent radiation. When the image / document is released from exposure to activating radiation, the fluorescent agent returns to the non-fluorescent state again. Such a feature may be useful, for example, for document authentication, because forged documents or photocopies do not have the ability to fluoresce and change appearance when exposed to activating radiation. The change between the fluorescent state and the non-fluorescent state can be repeated an unlimited number of times, for example from about 10 to about 100,000,000 times or more.
This feature also allows deliberate embedding of hidden information in the document, which is only revealed to those who know to expose the document to activation energy. . The hidden information can take the form of letters, text, images, etc., which form or pattern is provided by printing a toner containing a fluorescent agent. This information may indicate and / or authenticate the authenticity of images and / or documents formed using the toner set described herein.

  In an embodiment, the pattern formed by the toner containing the fluorescent agent may be machine readable code that stores digital data in the document. Digital data refers to information such as text or numbers in the form of digital codes representing zeros and ones, for example. The machine-readable code format can be, for example, a one-dimensional barcode, a two-dimensional barcode, a glyph, a dot, or a combination thereof. One-dimensional barcodes have the form as used for product UPC codes. Two-dimensional barcodes are, for example, PDF417 (based on stacked barcodes), 3-DI, Array Tag, Aztec code, Codblock, Code 16K, CP code, Data Matrix, Datastrip code, Maxicode, Minicode, etc. , Can be any suitable kind. The encoded information can also be in the form of data glyphs or dots.

  In order to embed digital data into an image formed with the toner set herein, the printer has an associated encoding device that receives the information to be encoded and the information is appropriately machine readable. Code to format. The encoded information is sent to a printer for printing on a paper substrate using toner containing a fluorescent agent. The device may also include a detector / reader for detecting and reading the hidden information when it is exposed by activation of the fluorescent agent. For this detection, the image is exposed to activation energy, causing the fluorescer to emit in different colors, and information is detected and read by the detector / reader while the different colors appear. The system may also include one or more processors, eg, for converting information into coded information representing that information, ie, converting information into a machine-readable code format. A similar processor to decode the coded information detected by the reader, i.e. convert the coded information to its original uncoded information format and recover the coded information It can also be used. Decrypted information can be presented to a person in a human readable format, thereby verifying the authenticity of the image and / or document and informing the hidden information contained in the document . One example use of this feature is to encode the actual amount of a check so that checks can be detected that may have changed the actual amount.

Any suitable substrate material that can be printed such as paper, plastic, cardboard, metal, etc. can be used as the recording medium. In an embodiment, the recording medium is paper. The paper may contain a fluorescent whitening agent as described in Patent Document 1, so that the image formed on the substrate is the result of fluorescence from the fluorescent agent and the result of the fluorescent whitening agent. As a synergistic effect with the emitted fluorescence. Fluorescent marks formed on a paper substrate with an optical brightener can be particularly advantageous as a result.
The above embodiments are now further illustrated by the following examples.

A black toner was prepared as follows.
An emulsion containing fluorescent polymer particles in water is prepared as follows. 134.5 g polypropoxylated bisphenol A-co-fumarate resin, 15.5 g carnauba wax, and 1.5 g DFKY-C7 lanthanide fluorescent agent (Risk Reactor) are dissolved in 1101 g ethyl acetate at 70 ° C. . Separately, 1.9 g DOWFAX 2A-1 solution and 3.0 g concentrated ammonium hydroxide are dissolved in 850.7 g deionized water at 70 ° C. The ethyl acetate solution is then slowly poured into the aqueous solution under continuous high shear homogenization (10,000 rpm, IKA Ultra-Turrax T50). After a further 30 minutes of homogenization, the reaction mixture is distilled at 80 ° C. for 2 hours. The resulting emulsion is stirred overnight, sieved through a 25 micron sieve and centrifuged at 3000 rpm for 15 minutes. Decant the supernatant to obtain an intense red fluorescent latex with an average particle size of 170 nm and a solids content of about 23.5%.

Next, a toner is prepared. 316 g of the latex, 32.5 g of Nexex 35 black pigment dispersion with a solids loading of 17 weight percent, 372 g of deionized water, and 1.87 g of DOWFAX 2A-1 solution were combined in a glass reactor and 0.3 N Adjust to pH 3.3 with nitric acid. While the mixture is homogenized (IKA Ultra-Turrax T50, 4000 rpm), a mixture of 2.2 g of 10 wt% Al ₂ (SO ₄ ) ₃ and 19.8 g of deionized water is added over 1 minute. The reactor contents are homogenized for an additional 5 minutes and then heated from room temperature to approximately 45 ° C. over 30 minutes with stirring at 495 rpm, at which point the particle size reaches 5.04 microns. Next, to form a shell around the agglomerated core, a further solution consisting of 131.8 g of the above latex and 0.72 g of DOWFAX 2A-1 solution is added to the reactor and the pH is adjusted to 0.3N with nitric acid. Adjust to 3 again and reduce the stirring speed to 385 rpm. The reactor temperature is increased by 3 ° C. over approximately 30 minutes, at which point the particle size reaches 6.02 microns. Next, the pH of the solution is adjusted to 7.5, and the stirring speed is reduced to 200 rpm. The reactor temperature is then raised to 70 ° C. over approximately 40 minutes and 5 drops of DOWFAX 2A-1 solution is added. The reaction mixture is maintained at 70-75 ° C. for 3 hours to obtain toner particles having a particle size of 6.21 microns. After cooling to room temperature, the mixture is sieved through a 20 micron metal sieve, filtered and dried. The toner is resuspended in deionized water for 40 minutes, filtered again, resuspended in water at pH 4.0 at 40 ° C. for 40 minutes, filtered again, and finally resuspended in water. The suspension is filtered and lyophilized to obtain black toner particles, which emit bright red fluorescence when exposed to UV light, have a particle size of about 5.90 microns, a GSD of about 1.25, A particle having a roundness of about 0.95.

  A similar black toner was prepared except that the fluorescent dye was omitted, and the toner had the same effective percentage of carbon black as the above toner.

  Next, an image is formed by xerography using toner. A large black rectangle is first formed on a paper substrate using toner that does not contain a fluorescent dye. The text “security message” is then transferred into a preformed black rectangle on the substrate using toner containing a fluorescent dye. Under ambient light, only the black rectangle is visible. When exposed to black light, the phrase “security message” appears in red where it is made of toner containing fluorescent dye in a black rectangle.

In the comparative example, a black toner containing the same fluorescent dye as described above is prepared as described above, but using a black dye colorant instead of a black pigment colorant.
Even when an image is formed on a paper substrate and exposed to black light, no color change or fluorescence is observed. This is considered to be because, unlike the black pigment, the black dye prevents the activation energy from reaching the fluorescent agent, thereby suppressing the fluorescence.

Claims (2)

  A toner set comprising a plurality of toners including a number of toners, wherein at least one toner comprises a binder, a colorant and a fluorescent agent, less than all of the toners of the toner set, and the remaining others The toner includes a binder and a colorant but does not include a fluorescent agent. At least the first toner group and the second toner group of the toner set form a combination, and the first and second toners of the combination are formed. The toner groups exhibit substantially the same color under ambient light conditions when imaged, and the first and second toner groups of the combination contain different amounts of the fluorescent agent and are activated When exposed to energy, the fluorescent agent fluoresces and the second toner in the color of the pattern formed in the image by the first toner group. The toner set, characterized in that to produce a visible change compared to.   An emulsion aggregation toner comprising a toner binder, a black pigment, and a lanthanide fluorescent agent.